We note that much of the challenge to CRU’s work has not always followed the conventional scientific method of checking and seeking to falsify conclusions or offering alternative hypotheses for peer review and publication. We believe this is necessary if science is to move on, and we hope that all those involved on all sides of the climate science debate will adopt this approach.

Because methodological challenges to scientists work that don't appear in Climate Journals controlled by the scientists in question are not part of the scientific method.

By the way, the statement that "The raw tree-ring data used in our published work are available; anyone is free to use them in any way they wish" is absolutely hilarious for anyone who has followed this saga over the years. To the extent they are available "freely," it is only because Steve McIntyre and other challengers of CRU's work engaged in a decade long legal campaign to get this publicly-funded data (necessary to verify and/or replicate the CRU's published work) released. Here is the McIntyre post to which CRU was responding, though they bend over backwards not to actually mention him.